Department of Chemical Engineering, Texas A & M University, College Station, TX 77843, USA.
Phys Chem Chem Phys. 2010 Mar 7;12(9):2209-18. doi: 10.1039/b917899f. Epub 2010 Jan 18.
Density functional theory is used for the evaluation of surface segregation, trends for dissolution of Pt surface atoms in acid medium, and oxygen reduction reaction activity of core-shell materials, containing a monolayer of platinum over a monometallic or bimetallic core. Two groups of cores are investigated: Pt/X with X = Ir, Au; Pd, Rh, Ag; Co, Ni, Cu; and Pt/Pd(3)X, with X = Co, Fe, Cr, V, Ti, Ir, Re. It is found that all the 4d and 5d pure cores may serve as stable cores, and their beneficial effect on the Pt monolayer may be further tuned by alloying the core to another element, here chosen from 3d or 5d groups. The Pd(3)X cores enhance the stability of the surface Pt atoms both in vacuum and under adsorbed oxygen; however the high oxygen philicity of some of the X elements induces their surface segregation that may cause surface poisoning with oxygenated species and their dissolution in acid medium.
密度泛函理论用于评估表面偏析、铂表面原子在酸性介质中溶解的趋势以及包含单层铂覆盖单金属或双金属核的核壳材料的氧还原反应活性。研究了两组核：Pt/X，其中 X = Ir、Au；Pd、Rh、Ag；Co、Ni、Cu；以及 Pt/Pd(3)X，其中 X = Co、Fe、Cr、V、Ti、Ir、Re。结果发现，所有的 4d 和 5d 纯核都可以作为稳定核，通过将核合金化到另一个元素（这里选自 3d 或 5d 组），可以进一步调整它们对单层 Pt 的有益影响。Pd(3)X 核在真空中和吸附氧下都增强了表面 Pt 原子的稳定性；然而，一些 X 元素的高氧亲合性导致它们的表面偏析，这可能导致表面被含氧物种中毒和在酸性介质中溶解。
